The invention relates to shackles used for joining two members under tension and more articularly to a locking shackle apparatus and a locking mechanism for the same.
The technique of attaching two members together under tension, such as a rope or cable, can be accomplished with the use of a shackle. In many instances such as in the field of sailing, it is desired to reduce to a minimum the distance between the attachment point of the line and the latching throat of the shackle. Such an instance occurs on a halyard when desiring to hoist the sail to the extreme top of the mast. In other instance, it is desired to reduce to a minimum the overall width and profile of the shackle such as to allow the shackle to pass through a Genoa block or other tight passage. In both cases, the desired arrangement consists of a thimble-like snap shackle onto which the line or cable can be directly spliced around its body.
Thimble-like rope type snap shackles such as described are commercially available but have many drawbacks. First, they are often subject to violent flogging and impact against a mast or are repeatedly dragged across a deck. Existing snap shackles are extremely prone to accidentally popping open under such circumstances. This accidental opening is so common that the current xe2x80x9cstate of the artxe2x80x9d procedure in the sailing industry has been to wrap masking tape around the shackle. A second drawback with current thimble type shackles is the difficulty in quickly opening or closing the shackle with limited sense of feel or sight. In many instances, sailors are in rough seas or are wearing gloves and it is not always possible to physically look at or feel the shackle when operating it. Existing thimble type shackles require the plunger knob to be precisely aligned before it can be operated, resulting in dangerous or inefficient situations. A third problem with existing thimble type rope shackles and with plunger pin shackles in general is that a high side loading is applied to the plunger pin. Frequently the plunger pin becomes permanently bent and the shackle is inoperative. Finally, a fourth problem with rope shackles and other shackles in general is the binding of the hook against deformed or fretted material along the inside of the clevis. After extended use, the constant pressure and sliding of a fitting latched to the shackle throat tends to deform and erode the material along the inside walls of the clevis slot. Eventually the clearance between the clevis wall and the pivoting hook decreases to a point where the hook begins to bind and no longer hinges correctly.
The earliest attempt to solve some of these problems was with a J-Lock shackle containing a plunger pin. However, these shackles did not have any method of locking the pin into place. As a result, the plunger pin would often pop open during either severe flogging or when dragged across the deck. These old J-Locks were cast from bronze and were produced at least 40 years ago and by some account, perhaps up to 100 years ago.
The next attempt to improve the shackle was a new design on the J-Lock that was made about 30 years ago. In this design, the knob on the plunger pin contained a notch, which had to be turned to the correct orientation so as to allow a keyway on the body to line up with the slot in the knob. To open the shackle, the knob would be turned to the correct orientation so as to allow the notch in the knob to pass over the keyway type protrusion on the body. To close the shackle, the notch would again be lined up, the plunger pin snapped shut, and the knob then turned to some random orientation so as to misalign the notch with the keyway protrusion.
While this J-Lock design was an improvement over the earliest version, there are several drawbacks with this design. First, during flogging, the knob tended to rotate from vibration and eventually work its way to the orientation such that the notch and keyway line up. Then, the shackle would pop open. Second, when pulled over a deck, the knob tended to roll and invariably rotate to the xe2x80x9cbadxe2x80x9d orientation whereas it eventually pops open. For years, the solution to this rotation and vibration problem has been to wrap tape around the knob and shackle so as to lock it in place. The tape must be ripped off whenever the shackle must be opened, and re-tapped the next time it is shut. This is very inconvenient and can be very dangerous to sailors in rough waters, but has been the only way to prevent opening during flogging or handling. The procedure has been the xe2x80x9cstate of the artxe2x80x9d for as long as most sailors can remember.
Thirdly, this J-Lock design is very difficult to quickly line up the notch with the keyway so as to open the shackle in a hurry. When the existing J-Lock is snapped shut and the knob rotated to a random position, it is difficult to find the position that allows the notch to line back up again. One must look or feel for the notch and keyway orientation, usually whilst the user is with gloves and cold fingers. During a sailboat race it is next to impossible to visually observe the orientation of the knob. Thus, the alignment must be done by sense of feel alone and becomes very frustrating.
A fourth problem with the existing J-Lock design pertains to the alignment of the knob.
In many cases, it is desirable to be able to quickly shut the shackle by snapping the hook shut as is done on conventional pull pin shackles. This quick shutting feature is particularly desirable during fast paced sailboat races. With the existing J-Lock, one must first pre-align the knob notch with the protrusion on the body. Assuming no change in orientation occurs, one should then be able to simply snap the hook shut. The hook pushes onto the free end of the pull-pin, forcing the knob to lift up past the body protrusion and then snaps back shut again. This is what would ideally be desired. However, with the existing J-Lock design, even the pre-alignment does not always allow the shackle to operate as desired. The contact of the hook with the free end of the pull-pin sometimes imparts a rotation onto the pull-pin which in turn misaligns the notch on the knob with the protrusion on the body. As a result of this misalignment, the knob jams into the bottom of the body protrusion and will not snap shut. Such a problem is extremely frustrating and causes the loss of valuable time in a sailboat race.
A fifth problem exists with the current J-Lock shackle. While loading a substantial amount of force onto the pull pin, the pull pin tends to bend and become permanently deformed. It any bending occurs, the pull pin cannot be slid open or closed and the shackle is destroyed.
And finally, the existing J-Lock hook geometry at the location where the hook pivots through the clevis case fosters fretting and destroys the shackle with continued use. When the hook is shut and the shackle loaded, the loaded member exerting force against the inside surface of the J-Lock is usually a metal ring or other metal fitting. After continued use, fretting and wear on the body clevis and hook surface causes the clevis and hook base material to xe2x80x9croll overxe2x80x9d on the edges. Burrs caused from this edge xe2x80x9croll overxe2x80x9d eventually reduce the clearance so much that the hook binds inside the clevis and will no longer open or shut smoothly.
Therefore a need exists in the art for an improved design of a shackle that will not accidentally open when exposed subject to violent flogging and impact against a mast or when repeatedly dragged across a boat deck, that overcomes the difficulty in quickly opening or closing the shackle with limited sense of feel or sight, that does not require high side loading to be applied to the plunger pin, and is not vulnerable to binding of the hook against deformed or fretted material along the inside of the shackle clevis.
The present invention relates to a shackle with a locking mechanism, the shackle is composed of a shackle body having a hook opening with a shackle pivot hole, a plunger pin opening for a plunger pin with a corresponding plunger pin exit, an anti-rotation plunger means such that the plunger pin opening is located on the anti-rotation plunger means, a hook body having a pivotal end having two sides and a hook pivot hole and a locking end, the pivotal end being pivotally connected within the hook opening of the shackle body by a pivot pin extending through the shackle pivot hole and hook pivot hole, the locking end having a slot corresponding to the plunger pin opening. The plunger pin has a free end and a transition to a smaller end, the smaller end of the plunger pin is axially inserted into the slot of the hook body and extends into the plunger pin opening in the shackle body. The plunger pin has two positions such that the two positions form corresponding settings for the shackle, whereby a closed setting is formed when the free end rests in the slot of the hook body, and an open setting is formed when the free end remains in the shackle body. There is a spring positioned around the smaller end of the plunger pin and located inside the plunger pin opening in the shackle body and constrained by the corresponding plunger pin exit in the shackle body, whereby compression and release of the spring creates the positions of the plunger pin. There is a knob attached to the smaller end of the plunger pin and resting on the anti-rotation plunger means on the shackle body, the knob having an opening that accepts the plunger pin, and a mating means on an axial face which mates with the anti-rotation plunger means such that when the mating means and the anti-rotation plunger means mate the locking mechanism is created whereby the plunger pin is locked into the one of the two positions, lifting the knob compresses the spring and allows the position of the plunger pin to change to the other position.
The present invention also relates to a locking mechanism for a shackle, the locking mechanism composed of a shackle plunger pin, the plunger pin has a free end and a transition to a smaller end. The locking mechanism is also composed of a spring positioned around the smaller end of the plunger pin, the plunger pin and spring located inside the shackle, the shackle has an anti-rotation plunger means and two positions, the positions are an open and a closed position. Also there is a knob attached to the smaller end of said plunger pin, the knob has an opening that accepts the plunger pin, and a mating means on an axial face which mates with the anti-rotation plunger means such that when the mating means and the anti-rotation plunger means mate the locking mechanism is created whereby the plunger pin is locked into a position. By lifting said knob compresses the spring and allows the position of said shackle to change to the other of the positions of the shackle.
Therefore, it is an aspect of the invention to provide an improved shackle apparatus which overcomes the deficiencies of the prior art shackle design.
It is another aspect of the invention to provide an improved shackle apparatus that simplifies the design of prior art shackle designs.
It is another aspect of the invention to provide an improved shackle apparatus that resists opening during flogging, impact or when dragged over a surface.
It is another aspect of the invention to provide a means of securing the plunger from motion by the use of a locking arrangement.
It is another aspect of the invention to provide an improved shackle apparatus that contains a xe2x80x9cdouble lockingxe2x80x9d plunger pin which is constrained from moving in both rotational and translational directions.
It is another aspect of the invention to provide an improved shackle apparatus that self-aligns the plunger knob so as to allow easy opening with limited reliance on sight and feel.
It is another aspect of the invention to provide an improved shackle apparatus that self-aligns the plunger knob so as to allow easy closing with limited reliance on sight and feel.
It is another aspect of the invention to provide an improved shackle apparatus that contains a plunger knob which can be rotated and placed in a xe2x80x9clockedxe2x80x9d position which resists both translational and rotational motion.
It is another aspect of the invention to provide an improved shackle apparatus that contains a knob which contains a mating means that can mate with an anti-rotation plunger means on the shackle body and prevent retraction of the plunger pin by preventing both rotation and lifting of the knob.
It is another aspect of the invention to provide an improved shackle apparatus that contains a plunger knob which is partially restrained from rotational motion when the shackle is being snapped shut so as to prevent the plunger knob from accidentally rotating into a misaligned position due to rotational force imparted to the free end of the plunger pin by contact from the closing hook.
It is another aspect of the invention to provide an improved shackle apparatus that contains a structural protrusion between the shackle body and the hook body so as to reduce the amount of stress carried by the plunger pin and increase the overall strength of the shackle.
It is another aspect of the invention to provide an improved shackle apparatus that consists of a hook opening which contains a contact surface which is xe2x80x9cproudxe2x80x9d with respect to the surface of the shackle clevis so as to allow any applied force to aid in holding the hook against the shackle body when the plunger pin is snapped closed.
It is another aspect of the invention to provide an improved shackle apparatus that allows a rope or cable to be directly spliced over the body.
It is another aspect of the invention to provide an improved shackle apparatus that can be passed through a pulley block or other tight passage.
It is another aspect of the invention to provide an improved shackle apparatus that contains a minimal distance between the spliced attachment point and the member which the shackle attaches to.
It is another aspect of the invention to provide an improved shackle apparatus which can be set into in a locked and secured state so as to allow the user to be aware of the engagement of the locked state with a minimal reliance on sight or feel.
It is another aspect of the invention to provide an improved shackle apparatus which can be easily switched from an unlocked state to a locked state and vise versa.
It is another aspect of the invention to provide an improved shackle apparatus which resists opening due to accelerations in any translational or rotational direction.
It is final another aspect of the invention to provide an improved shackle apparatus that attempts to reduce binding of the hook inside the clevis due to wear or fretting.
These aspects of the invention are not meant to be exclusive and other features, aspects, and advantages of the present invention will be readily apparent to those of ordinary skill in the art when read in conjunction with the following description, appended claims and accompanying drawings.